Preparative Organic Photochemistry

Preparative Organic Photochemistry

By

Alexander Schonberg Technische Universitat Berlin

In cooperation with

GUnther Otto Schenck . Otto-Albrecht NeumUller

Abteilung Strahlenchemie Max-Planck-Institut fur Kohlenforschung Mulheim(Ruhr

Second completely revised edition of "Praparative OrganischePhotochemie"

by A. SchOnberg with a contribution by G. O. Schenck

Springer-Verlag New York Inc. 1968

ISBN-13: 978-3-642-87920-3 e-ISBN-13: 978-3-642-87918-0 DOl: 10.1007/978-3-642-87918-0

All rights reserved. No part of this book may be translated or reproduced in any form without written permission

from Springer-Verlag. © by Springer-Verlag Berlin • Heidelberg 1968

• Library of Congress Catalog Card Number 67-16134

softcover reprint of the hardcover 1 st edition 1968

Sat.: Werk- und Feindruckerei Dr. Alexander Krebs, Weinheim/Bergstr. und Bad Homburg v. d. H.

The use of general descriptive names, trade names, trade marks, etc. in this publication, even if the former are not

especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise

Marks Act, may accordingly be used freely by anyone

Tide-No. 1382

Preface to the First Edition (Abridged and translated)

Organic photochemistry may be divided into three parts: theory which is the province of the physical chemist; instrumentation which requires the skill of both physicist and engineer; and preparation which falls within the sphere of the organic chemist.

At one time the same person could cover all three fields without too much difficulty, but this has now become virtually impossible because the disciplines involved have expanded in both breadth and depth; it is there­fore timely to have a separate treatment of preparative organic photo­chemistry.

There appears to be no review of the main photochemical reactions which includes the advances made in recent years available to the organic chemist working in the preparative field. An exception is the excellent "Photochemical Reactions" by C. R. MASSON, V. BOEKELHEIDE and W. A. NoYES JR., published in 1956, which gives a brief review of the reactions which are important in preparative organic photochemistry. The present monograph on the other hand seeks to provide a detailed survey for the chemist; the author does not set out to discuss every photo­chemical reaction in the field of organic chemistry but he does include in addition to those of current interest in the preparative field some which are likely to be of interest in the future and which result in single end-products of known composition. The photochemical synthesis of highly polymerized products falls outside the scope of the work.

The author hopes his book will not only show chemists what has been achieved already but will also stimulate them to make greater use of photochemical reactions than heretofore. This is not possible, however, unless the basic principles of theory and instrumentation are thoroughly known. The author wishes to thank Prof. G. O. SCHENCK for his contribution, "General remarks on carrying out photochemical reactions", which supplies this knowledge.

As regards future work, it should be noted that it is not sufficient merely to publish the results of experiments carried out in the light but that the results of equivalent experiments in the dark must also be given.

VI Preface

Older publications, in particular, often describe reactions which occurred under irradiation but lack data on parallel experiments where light was excluded, so that the material presented does not allow us to decide whether the light was indispensable in such cases or whether it merely accelerated the reaction.

The author does not wish to conclude without thanking his Egyptian colleagues, and in particular Professor AHMED MUSTAFA, for their assistance with his photochemical work.

Cairo, June 1957 A. SchOnberg

University and National Research Centre

Preface to the Second Edition

The same guiding principles laid down for the first edition have been followed in the second. Since the first edition came out, our knowledge in the field of preparative organic chemistry has grown in both range and depth to an amazing extent. Most of the material dealt with in this edition was unknown when the first edition was compiled, so that the present edition may be said to be an essentially new book.

The indexes have been greatly enlarged and new lists of relevant mono­graphs and review articles have been compiled. As regards nomenclature, the present edition follows the IUP AC Rules. References have been included up to the end of 1965, and a few results from the authors' own laboratories have been inserted, although they were not at that time available in print.

It is the intention of the publishers and the authors to bring the work up-to-date by the periodical issue of supplementary volumes. In a field which is growing so fast it seems best not to await a possible third edition before summarizing the results.

Acknowledgements: Our sincere thanks are due to F. SCHALLER for the compilation of data pertaining to irradiation technique, to C. MAUCY (IBM Dusseldorf) for writing the Compound Index program, to R. BERN­HARDT and V. KUBE (Zentralstelle fUr Maschinelle Dokumentation, Frank­furt, Direktor K. SCHNEIDER) for the KWOC program and to Mrs. M. LEHMANN for proofreading. We are grateful to the publishers for their interest and encouragement.

Berlin

Miilheim/Ruhr

August 1967

A. Schonberg

G. O. Schenck

O.-A. Neumuller

Contents

Chapter 1

Photoisomerization of unsaturated systems proceeding with the formation of four-membered homocyclic rings

1. Formation of cyclobutane derivatives by intramolecular addition between non-conjugated olefinic linkages (CIAMlcIAN-addition) . 1

2. Photochemical valence tautomerization of l,3-dienes 4 a) Homoannular 1,3-dienes 4 b) Aromatic compounds . 9 c) Transoid 1,3-dienes 10

3. Intramolecular dianthracene formation 11

References . 12

Chapter 2

Photoisomerization of dienes and trienes not leading to the formation of cyclobutane derivatives

1. Photoisomerization of open chain 1,3-dienes to 1,2-dienes

2. Photoisomerization of 1,3-cyclohexadienes a) Cleavage to 1,3,S-hexatrienes b) Rearrangement to bicyclo[3.1.0lhex-2-enes

3. Photoisomerization of 1,S-cyclooctadienes

4. Photoisomerization of 1,3,S-hexatrienes to 1,3-cyclohexadienes

5. Photoisomerization of an acene involving loss of aromaticity

References .

Chapter 3

14

14 14 16 18

18

20

21

Photoisomerization of aldehydes and ketones not leading to the formation of oxygen heterocycles

1. Photoisomerization of 1X,[3-unsaturated carbonyl compounds to [3,y-unsaturated or cyclopropyl isomers 22

2. Photoenolization of aromatic ketones . 24

3. Photoisomerization of saturated ketones via photoelimination 25

Contents IX

4. Photoisomerization of O(,~-unsaturated carbonyl compounds via cyclization 27 a) Cyclization of citral 27 b) Rearrangement of eucarvone 27 c) Rearrangement of verbenone 28

5. Photoisomerization of cross-conjugated cyclohexadienones 28 a) Simple 2,5-cyclohexadien-1-ones 29 b) Condensed 2,5-cyclohexadien-1-ones 29

References 32

Chapter 4

Various photoisomerizations of ketones, esters and halides

1. Isomerization of ketones to tertiary alcohols by intramolecular cyclization 34 a) Cyclobutanols from saturated cyclic and acyclic ketones 34 b) 2-Hydroxycyclobutanones from 1,2-diketones 35 c) Cyclobutanols in the steroid series 36 d) Cyclohexenols from non-conjugated ketones 37

2. Photorearrangement of enol and dienol esters 37

3. Isomerizations with migration of bromine atoms 39

4. Light-induced VON AUWERS rearrangement 40

References 40

Chapter 5

Photoisomerizations involving formation and transformation of five or six membered heterocyclic oxygen compounds

1. Photochemical formation of heterocyclic oxygen compounds 41 a) Formation of furan derivatives by intramolecular cyclization 41 b) Formation of pyran derivatives by intramolecular cyclization 41 c) Formation of heterocyclic oxygen compounds by isomerization of cyclic ketones 43

2. Photoisomerization of heterocyclic oxygen compounds to open chain compounds 44 a) Photoisomerization of furan derivatives 44 b) Photoisomerization of cyclic acetals to esters 45

3. Photochemical rearrangements among heterocyclic oxygen compounds 46 a) Isomerization of a 4H-pyran to a 2H-pyran 46 b) Isomerization of epidioxides 46

References 47

Chapter 6

Photoisomerizations involving nitrogen compounds

1. Photoisomerizations with rupture of nitrogen-oxygen bonds a) Amides from aldoximes b) Anilides from nitrones c) Oxaziridines from nitrones

48 48 48 50

x Contents

d) Unsaturated lactams from heterocyclic N-oxides e) 2-Hydroxyazobenzenes from azoxybenzenes

2. Photoisomerization with rupture of nitrogen-halogen bonds

3. Photoisomerizations with rupture of nitrogen-carbon bonds a) Rearrangement of a pyrimidine b) Rearrangement of pyrazoles

References

Chapter 7

Photochemical stereoisomerization

51 53

53

54 54 54

55

1. Photochemical cis-trans isomerizations at double bonds 56 a) Compounds containing isolated C=C bonds 57 b) Dienes and polyenes 58 c) Indigoid systems 61 d) Azo compounds 62 e) Compounds containing C=N bonds 63

2. Photochemical cis-trans isomerizations of cyclopropane and cyclobutane derivatives 64

3. Photoepimerizations 65 a) Epimerization at carbon atoms 65 b) Epimerization at sulfur atoms 66

References 67

Chapter 8

Photodimerization with formation of cyclobutane derivatives (Cyclodimerization)

1. Stilbene and related compounds

2. Unsaturated hydrocarbons a) Acyclic dienes b) Cyclic olefins c) Cyclic dienes

3. (X,~-Unsaturated ketones a) Acyclic (X,~-unsaturated ketones. b) Cyclic (X,~-unsaturated ketones c) l,4-Quinones

4. (X,~-Unsaturated acids and related compounds a) Derivatives of maleic and fumaric acids b) Cinnamic acids

5. Coumarin and isocoumarin a) Coumarin b) Isocoumarin c) Furocoumarins

6. 2,6-Dimethyl-4-pyrone

7. Tetraphenylbutatriene

70

73 74 74 75

75 76 77 79 82 82 83

85 85 87 87

89 89

Contents

8. Unsaturated sulfur compounds a) Benzo[b]thiophene 1,1-dioxide b) 2-Nitrobenzo-l,4-dithiin

9. Thymine and related pyrimidine derivatives

10. ~-Lumicolchicine

11. Acetylene compounds

References

Chapter 9

Photodimerizations involving formation of eight-membered rings

1. Carbocyclic aromatic compounds a) Naphthalene derivatives b) Anthracene and derivatives c) Higher condensed aromatic compounds

2. Heterocyclic nitrogen compounds a) Pyridine derivatives b) Condensed nitrogen heterocyclic compounds

3. Heterocyclic oxygen compounds

References

Chapter 10

Various photodimerizations involving aldehydes, halides and thiocarbonyl compounds

1. Photodimerization of aliphatic compounds

a) Butyraldehyde b) Dimerization of halides c) Dimerization of thiocarbonyl compounds

2. Photodimerizations of aromatic aldehydes

References

Chapter 11

XI

90 90 90

91

92

92

94

97 97 97 99

99 99

101

102

103

105

105 105 106

107

108

Cycloaddition of alkenes or alkynes to other alkenes or aromatic nuclei leading to the formation of four-membered rings. Photolyses involving retro-cycloaddition

1. Addition of maleic anhydride to benzene and related aromatic compounds including furan and thiophene 109

2. Addition of maleic acid derivatives to alkenes 110

3. Addition of 2-methyl-2-butene to benzonitrile 111

4. Photochemical cycloaddition of IX,~-unsaturated ketones to alkenes 112 a) 2-Cyclohexenone and isobutylene 112 b) Cyclopentenone and cyclopentene 112 c) 2,4-Pentanedione or dimedone and cyclohexene 113

XII Contents

5. Photochemical cycloaddition reactions of acetylene compounds 114 114 115 115 115

a) Addition to benzene and derivatives b) Addition to cyclopentenone c) Addition to dimethyl cyclobutene-1,2-dicarboxylate d) Addition of diphenyl acetylene to naphthalene

6. Photolyses involving retro-cycloaddition a) Photolysis of dehydronorcamphor b) Photochemical synthesis of bullvalene via retro-cycloaddition

References

Chapter 12

116 116 116

117

Photochemical cycloaddition of 1,2-quinones, 1,2-diketones and 1,2,3-triketones to multiple bonds

Photochemical cycloaddition of 1,2-quinones, 1,2-diketones and 1,2,3-triketones to multiple bonds 118

References 125

Chapter 13

Photochemical cyclization of aromatic compounds via elimination of hydrogen and/or halogen atoms. Formation of carbocycles

1. Formation of five-membered homocycles. A fluorene derivative from triphenyl-methyl 126

2. Formation of six-membered homocycles 127 a) Phenanthrenes from stilbenes 127 b) Fused aromatic compounds from o-dibenzylidene compounds 129 c) Phenantbroperylenediones, dibenzoperylenediones and analogous compounds

from less condensed aromatic precursors 131 d) Dehydrocyclization of some fused heterocyclic hydrocarbons 134

References 137

Chapter 14

Photochemical dehydrocyclization of aromatic compounds via elimination of hydrogen atoms. Formation of heterocycles

1. Formation of five-membered heterocycles. Carbazoles from diphenylamines 138

2. Formation of six-membered heterocycles 138 a) Benzocinnolines from azobenzenes 138 b) Phenanthridines from Schiff's bases 141 c) Phenanthridizinium salts from styrylpyridinium salts 142 d) Benzo[c]tetrazolo[2,3-a]cinnolinium salts from triphenyltetrazolium salts 143

References 144

Contents

Chapter 15

Photochemical dehydrodimerization

1. Dehydrogenation by oxygen

2. Dehydrogenation by carbonyl compounds

3. Dehydrogenation by dyes

4. Dianthracene from dihydroanthracene

References

Chapter 16

Photochemical dehydrogenation

1. Quinones as dehydrogenating agents

2. 1,2-Disulfides as dehydrogenating agents

3. Photosensitized dehydrogenation using dyes

References

Chapter 17

XIII

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147

148

149

150

151

152

153

154

Photochemical additions to carbon-carbon multiple bonds not resulting in ring formation

1. Water

2. Hydrogen peroxide (MILAS reaction)

3. Hydrogen bromide

4. Nitrosyl chloride

5. Alcohols, ethers, and tert. butyl hypochlorite a) Alcohols b) Ethers c) Tert. butyl hypochlorite

6. Sulfur compounds a) Hydrogen sulfide, thiols and thiocarboxylic acids b) Sulfenyl chlorides c) Sulfonyl chlorides

7. Ammonia, amines and formamide a) Ammonia and amines b) Formamides

8. Dimethylmaleic anhydride

9. Aldehydes and ketones a) Aldehydes b) Ketones

10. Aliphatic polyhalides a) Polyhalides not containing fluorine b) Polyfluoroalkyl iodides c) Photoaddition of polyhalides to conjugated systems

155

157

157

159

159 159 160 162

162 162 164 165

165 165 166

168

169 169 169

170 171 173 175

XIV Contents

11. Organophosphorus compounds 176 a) Phosphines 176 b) Phosphonates 177

12. Organosilicon compounds 178 a) Trichlorosilane 178 b) Organosilicon compounds 179

13. Organogermanium compounds 179

References 180

Chapter 18

Photochemical addition reactions of 1,4- and 1,2-quinones with alkyl benzenes or with ethers

1. Addition of chloranil to hydrocarbons

2. Addition of phenanthrenequinone to hydrocarbons

3. Addition of phenanthrenequinone or tetrachloro-o-quinone to ethers

References

Chapter 19

182

182

184

185

Photochemical additions of aldehydes to quinones, quinone imines and quinone oximes

1. Addition of aldehydes to 1,2-quinones

2. Addition of aldehydes to l,4-quinones

3. Addition of aldehydes to quinone imines and quinone oximes a) Quinone imines b) Quinone oximes

References

Chapter 20

Photoreductions with the aid of alcohols, ethers and other hydrogen donors

186

188

190 190 191

192

1. Photoreductions of C=C bonds 193

2. Photoreductions of C=O bonds. Formation of benzhydrols 194

3. Photoreductions of C=N bonds 195

4. Photoreductions of gem. chloronitroso compounds. Formation of oximes 197

References 197

Chapter 21

Formation of carbinols by photochemical addition of ketones and aldehydes to methylene groups

1. Addition of ketones

2. Addition of aldehydes

References

198

201

202

Contents

Chapter 22

Photochemical formation and photolysis of 1,2-ethanediols

1. Formation of 1,2-ethanediols by the addition of alcohols to ketones

2. Formation of 1,2-ethanediols via reductive dimerization a) Aldehydes b) Monoketones c) 1,2,3-Triketones d) ot-Ketocarboxylic acids and o-acylbenzoic acids

3. Photochemical cleavage of 1,2-ethanediols by carbonyl compounds

References

Chapter 23

Photochemistry of deoxybenzoin derivatives

Photochemistry of deoxybenzoin derivatives

References

Chapter 24

Photochemical decarbonylation

1. Decarbonylation of ketones a) Saturated cyclic ketones b) Unsaturated cyclic ketones c) Aromatic ketones

2. Decarbonylation of a ketene

3. Decarbonylation of aldehydes 4. Decarbonylation of S-acyl xanthates

References

Chapter 25

xv

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203 203 204 209 210

211

213

215

217

218 218 220 220

222

222 223

224

Photochemical formation and reactions of carboxylic acids and their derivatives

1. Formation of aliphatic carboxylic acids by the action of oxygen and water on alkyl halides 225

2. Formation of carboxylic acids by photolysis of cyclic ketones 225 a) Saturated ketones 225 b) Unsaturated ketones 227

3. Formation of acid derivatives 230 a) Amides 230 b) Lactones 231 c) Acyl chlorides 233

XVI Contents

4. Photochemical reactions of esters involving the acyloxy groups a) Rearrangements of esters b) Reductive elimination of an acetoxy group c) Light-induced FRIES rearrangement

5. Further formation modes of esters a) Formation of IX-ketocarboxylates from IX-keto acetals b) Formation of esters from 2-butene-1,4-diones c) Formation of an ester from a diflavylene compound

6. Formation of fluorenecarboxylic acids by photolysis of fluoranthenols

References

Chapter 26

Photochemical reactions with N-halogenated amines

1. Photochemical replacement of chlorine in N-chloroamines by hydrogen

2. The light-induced HOFMANN-LoFFLER reaction a) Synthesis of pyrrolidines b) Synthesis of bridged nitrogen compounds c) Synthesis of conanines d) Synthesis of pyrrolizidines

3. Formation of chloroalkylamines from N-chloroamines a) N-Butyl-4-chlorobutylamine b) Molecular rearrangements of steroidal N-chloroamines

References

Chapter 27

Photochemical transformations of organic nitrites

1. Photochemical reactions of nitrites involving fission of oxygen-nitrogen bonds.

234 234 235 236

238 238 238 239

239

240

242

242 242 244 244 245

246 246 246

247

The BARTON reaction 248 a) Simple aliphatic and alicyclic nitrites 248 b) Epimerization in nitrite photolysis 249 c) Steroidal nitrites 250

2. Photochemical reactions of nitrites involving fission of carbon-carbon bonds 251 a) Syntheses of nitrosoalkanes 251 b) Hydroxamic acids 252 c) Fragmentation reactions in the steroid series 253

References 254

Chapter 28

Photochemical dealkylation of nitrogen compounds

1. Photolysis of N-alkyl and N-aralkyl amines

2. Photolysis of N-alkyl nitrogen heterocycles

References

255

257

258

Contents XVII

Chapter 29

Photochemical introduction of cyano and nitroso groups

1. Formation of nitriles 260

2. Formation of geminal chloronitroso and dimeric nitroso compounds 261

3. Formation of diphenylfuroxan via oc-chloro-oc-nitrosotoluene 262

4. Formation of oximes from hydrocarbons through photolysis ofNOCI or NO/CI2

mixtures 262 a) Photolysis of NOCl 263 b) Photolysis of NOCI in the presence of HCI or NO 263 c) Photolysis of NO, CI2 and HCI 263

References 265

Chapter 30

Photochemical transformations of unsaturated nitro compounds

1. Photolysis reactions of unsaturated nitro compounds 266

2. Photochemical conversion of aromatic nitro compounds to nitroso compounds 267

3. Photoreduction of an aromatic nitro compound to an aniline derivative 270

4. Photocyclization reactions of aromatic nitro compounds 271

References 273

Chapter 31

Light-induced reactions of diazoalkanes, diazirines and related compounds

1. Photoaddition reactions of carbenes to unsaturated systems resulting in ring formation 275 a) Formation of cyclopropane compounds 275 b) Formation of oxide rings 279 c) Formation of aziridine rings . 280 d) Formation of cyclopropene compounds 281

2. Photoaddition reactions of carbenes to saturated compounds resulting in insertion into sigma bonds 281 a) Insertion into C-C, c-o and C-halogen bonds 281 b) Insertion into C-H bonds 283 c) Insertion into O-H bonds 286 d) Insertion into N - H bonds 287

3. Photodimerization reactions of carbenes 288

4. Miscellaneous photochemical reactions of carbenes 290 a) Isomerization reactions with formation of olefins 290 b) Univalent hydrogenation with subsequent dimerization 290 c) Addition to oxygen 291

5. Photolysis of diazirines 291

6. Addition of diazomethane to olefins with formation of a pyrazoline 292

References 292

XVIII Contents

Chapter 32

Photochemical syntheses with diazoketones, quinone diazides and iminoquinone diazides

1. Acyclic mono-diazo ketones a) Conversion to ketenes and oc,~-unsaturated ketones b) Photolysis in the presence of water or alcohol c) Photolysis in the presence of N-methylaniline and ethanethiol d) Photolysis in the presence of azo compounds e) Photolysis in the presence of azomethines f) Replacement of the diazo group by hydrogen g) Intramolecular addition of a carbene

2. Acyclic bis-diazoketones

3. Cyclic oc-diazoketones a) Ring contraction of five-membered rings b) Ring contraction of six-membered ring systems c) Ring contraction of o-quinone diazides (Sus reaction) d) Photolysis of cyclic oc-diazoketones not leading to ring contraction

4. Azo dyes from quinone diazides

5. p-Quinone diazides and p-iminoquinone diazides

References

Chapter 33

Photochemical syntheses with diazonium salts and diazosulfonates

294 294 295 297 298 299 300 300

301

301 302 303 304 306

309

310

312

1. Reductive deamination of diazonium salts 313

2. Replacement of the diazonium group by halogen or the hydroxy group 314

3. Photolysis of diazonium salts as a method of cyclization 315

4. Change in reactivity of aryl diazosulfonates 316

5. Photolysis of a 1,2,3-thiadiazine S,S-dioxide 316

References 317

Chapter 34

Synthetic applications of light-induced reactions of azides

1. Photolysis of alkyl azides 319

2. Photolysis of aryl azides 320 a) Carbazoles and 4-phenylbenzofuroxan from 2-azidobiphenyl derivatives 320 b) Photochemical conversion of aryl azides to azo compounds 321

3. Photolysis of acyl azides 321 a) The light-induced CURTruS rearrangement 321 b) Formation of lactams 322 c) Formation of amides 324

4. Photochemical reaction of ethyl azidoformate 324 a) Reaction with cyclic hydrocarbons 324 b) Reaction with alcohols 325

Contents

5. Photochemical syntheses with sulfonic acid azides a) Photolysis in methanol b) Photolysis in sulfoxides c) Photolysis in sulfides

References

Chapter 35

XIX

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327

Photolysis of pyrazolines, pyrazoles, azo compounds, 1,2,3-thiadiazoles, and p-benzoquinone diimine N,N'-dioxides

1. Photolysis of pyrazolines

2. Photolysis of pyrazoles

3. Photolysis of diaroyl azo compounds

4. Photolysis of 1,2,3-thiadiazoles

5. Photolysis of p-benzoquinone diimine N,N'-dioxides

References

Chapter 36

Miscellaneous light-induced reactions of organic nitrogen compounds

1. Incorporation of C1 or C2 fragments by the photochemical reaction of various

328

329

330

331

332

333

nitrogen compounds with alcohols 334 a) Benzo[f]quinolines from SCHIFF'S bases. 334 b) Imidazolidines from diamines or from SCHIFF s bases. 335 c) Oxazolidines from SCHIFF'S bases 335

2. Photolysis of oxadiazolinones 337

3. Light-induced abnormal benzidine rearrangement 337

4. Light-induced condensations involving primary amines and aldehydes 338

5. Aromatic nitriles by photochemical cleavage of aromatic aldazines 339

References 339

Chapter 37 Photo halogenation

1. Photohalogenation. Scope of the reaction

2. Photochlorination a) Chlorination of benzene in the presence of iodine b) Chlorination of benzene in the presence of maleic anhydride c) Replacement of the sulfonyl chloride group by chlorine d) Replacement of the nitroso group by chlorine e) Replacement of alkyl groups by chlorine f) Solvent effects on the site of attack by chlorine g) Chlorination of a cyclic trisulfone

3. Photobromination a) Migration of alkyl groups during bromination b) Bromination in the presence of oxygen c) Bromination in the allylic position with the aid of bromine d) Bromination with chlorine-bromine mixtures . e) Orienting effects in the photobromination of alkyl bromides f) Bromination of aryl selenocyanates

341

344 344 345 346 347 347 348 349

349 349 350 351 351 351 353

xx Contents

4. Photoiodination 353

5. Photohalogenation with the aid of inorganic and organic halides 354 a) Experiments with iodine chloride 354 b) Chlorination with sulfuryl chloride 354 c) Chlorination with trichloromethanesulfonyl chloride 355 d) Chlorination with trichloromethanesulfenyl chloride 356 e) Chlorination and bromination with the aid of N-chloro- and N-bromo-

succinimide 356 f) Bromination with the aid of dibromodimethylhydantoin 359

References 360

Chapter 38

Photochemical conversions of organic halides

1. Replacement of bromine by hydrogen, chlorine or 82Br 362 a) Replacement of bromine by hydrogen 362 b) Replacement of bromine by chlorine or 82Br 362

2. Replacement of iodine in iodides by hydrogen, nitric oxide or chlorine 363 a) Experiments with aliphatic iodides 363 b) Chlorobenzene from iodobenzene by photochemical decomposition of iodine

chloride 365

3. Deiodination of aliphatic iodides 365

4. Debromination of 1,1-diaryl-2-bromoethylenes 366

5. Formation of organomercury compounds by the action of mercury on alkyl iodides 366

6. Preparation of hexaarylethanes by the action of triarylmethyl halides on tri-arylmethanes 367

7. Photolysis of aromatic iodo compounds 368 a) Iodobenzene and related substances 368 b) Formation of benzyne on photolysis of 1,2-diiodobenzene or (2-iodophenyl)-

mercury iodide 368

8. Photolysis of alkyl hypoiodites, acyl hypoiodites and N-iodoamides 369 a) Photolysis of alkyl hypoiodites. Preparation of ethers 369 b) Photolysis of acyl hypoiodites. Replacement of the carboxyl group by iodine 370 c) Photolysis of N-iodoamides. Preparation of lactones 370

References 371

Chapter 39

Photochemical formation of hydroperoxides and peroxides

1. Replacement of hydrogen by the hydroperoxide group a) Unsensitized photooxidation of unsaturated compounds b) Photosensitized oxidation of olefins c) Photosensitized oxidation of secondary alcohols d) Photooxidation of ethers e) Photooxidation of nitrogen compounds f) Photooxidation of a phenol

2. Transannular peroxides from cyclic 1,3-dienes a) Epidioxides from alicyclic 1,3-dienes b) Epidioxides from fused 1,3-cyclohexadienes

373 373 375 379 379 380 382

382 383 385

Contents

c) Epidioxides from acenes d) Photooxidation of carbo- and heterocyclic cyclopentadienes

3. Photochemical formation of bis-aralkyl and bis-acyl peroxides a) Formation of six-membered cyclic peroxides b) Formation of open chain peroxides c) Formation of acyl peroxides

4. Miscellaneous photochemical oxidation reactions a) Oxidative cleavage of C-C bonds b) Photooxidation of Curare alkaloids

References

Chapter 40

Photochemical formation and transformations of epoxides

1. Photochemical formation of epoxides

2. Photoisomerization of epoxy ketones a) Acyclic ot,~-epoxyketones b) Acyclic ~, y-epoxyketones c) Cyclic ot,~-epoxyketones d) Steroid ot,~-epoxyketones

References

Chapter 41

Photochemical formation of four membered rings with one oxygen atom

(PATERNO-BOeHl reaction)

XXI

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397 397 398 399

400 401 401

402

407

408 408 409 409 412

413

1. Formation of oxetanes 414 a) Cycloaddition of aldehydes or ketones to oleflns 414 b) Intramolecular cycloaddition leading to oxetanes 417 c) Cycloaddition of p-quinones to oleflns leading to spirooxetanes 418 d) Cycloaddition of 1,2-dicarbonyl compounds to olefins leading to ot-keto-

oxtanes . 419 e) Formation of oxetanes bearing functional groups 420

2. Formation of oxetes as intermediates in the cycloaddition of carbonyl compounds to acetylenes 423

3. Cycloaddition of p-benzoquinone to conjugated dienes not resulting in formation of oxetanes 424

References 424

Chapter 42

Photochemical formation and reactions of furans

1. Photoisomerization of quinoid compounds to furan derivatives

2. Photochemical reactions of furans with oxygen a) Simple furan derivatives b) Fused furan systems c) Aryl furans d) [2.2](2,5)Furanophane

3. Photoaddition of methanol to a furan derivative

References .

426

427 427 429 430 432 432

433

XXII Contents

Chapter 43

Photochemical formation and transformations of organic sulfur compounds

1. Photochemical syntheses using S02, S02Cl2 and SCl2 434 a) Sulfochlorination 434 b) Sulfenylchlorination 437 c) Sulfoxidation 438 d) Cyclic sulfates from sulfur dioxide and o-quinones 439

2. Photochemical formation and transformations of sulfides 439 a) Thioethers from di- and trisulfides 439 b) Photolysis of 9,9'-bis-(phenylthio)-9,9'-bifluorene 440 c) Insertion reaction of mercury with disulfides 441 d) Conversion of a disulfide to a sulfenyl chloride 441 e) Action of mercaptoacetic acid on benzo[a]pyrene 442 f) Photolysis of a dixanthate 442

3. Photochemical thiocyanation 443

4. Photooxidation 444 a) Sulfoxides 444 b) Thiourea 444 c) Conversion of thioketones into ketones 445 d) Co-oxidation of thiols and olefins by oxygen 446

5. Miscellaneous photochemical reactions of sulfur compounds 447 a) Photolysis of sulfones 447 b) Photolysis of unsaturated sultones 448 c) Photolysis of thiobenzophenone in the presence of olefins 448 d) Photochemical formation of a dipyridyl sulfide from a l,4-dihydropyridine-

thione 449 e) Photochemical reactions involving extrusion of sulfur from dithietanes and

thiiranes 450 f) Photochemical aryl migration in arylthiophenes 451

References 451

Chapter 44

Photochemical reactions of organophosphorus and organoarsenic compounds

1. Organophosphorus compounds a) Light-induced addition of dialkyl phosphonates to quinones b) Photochemical reactions of trialkyl phosphites c) Photolysis of triarylphosphines d) Photochemical synthesis of phosphonium salts e) Photolysis of tetraarylphosphonium salts

2. Organoarsenic compounds

References

Chapter 45

Photochemical formation and reactions of organometallic compounds

1. Light-induced formation of organometallic carbonyl compounds from metal

453 453 454 455 455 457

457

458

carbonyls and organic compounds . 459

2. Photochemical reactions of organometallic carbonyl compounds 462 a) Substitution reactions with electron donors 462

Contents XXIII

b) Photochemical decarbonylation of organometallic acyl derivatives to alkyl derivatives 464

3. Photochemical reactions of organotin compounds 465 a) Light-induced reaction of hexamethylditin with trifluoroiodomethane 465 b) Synthesis of 1,2,3-triphenylazulene by photolysis of an organotin compound 465 c) Photosensitized oxygenation of organotin compounds 466

4. Photochemical reactions of organomercury compounds 466 a) Photolysis reactions with formation of arylmercury halides 467 b) Photolysis reactions with formation of mercury 467

5. Miscellaneous photochemical reactions of organometallic compounds 468 a) Light-induced formation of a GRIGNARD reagent from an aliphatic bromide 468 b) Photodimerization of a metal-complexed olefin 468 c) Photolysis of aromatic lithium compounds 469 d) Photolysis of iron pentacarbonyl in nitrobenzene solution 469

References 470

Chapter 46

Light sources and light filters in preparative organic photochemistry G. O. SCHENCK

1. Light sources a) Low-pressure sodium vapor lamps b) High-pressure sodium vapor lamps c) Low-pressure mercury lamps d) High-pressure mercury lamps e) Super-high-pressure mercury lamps f) Super-high-pressure xenon-mercury lamps. g) High-pressure xenon lamps h) Sunlight i) Incandescent lamps j) Halogen incandescent lamps k) Fluorescent tubes . 1) Vortex-stabilized plasma lamps m) Low-pressure gas discharge lamps for the far UV n) Flash lamps 0) Lasers .

Tables .

2. Light filters a) Solid filter materials b) Liquid filters . c) Interference filters d) Reflection interference filters

References .

A selective bibliography on photochemistry

Author Index

Reaction Index .

Sensitizer Index

Compound Index

472 474 475 475 475 476 477 477 477 477 478 478 478 478 479 479 479

490 490 491 492 493

494

495

501

523

559

560